An epidemiological and clinical study of snake-bites in childhood.

The last decade has seen major changes in the first-aid management of elapid snake-bites and the introduction of a new venom-detection kit which can identify the genus of medically-important snakes. In the light of these developments, we report a 10-year study that comprised 218 consecutive children who were admitted to hospital in southeast Queensland, after a confirmed or a suspected snake-bite. One-third (34.9%) of victims were preschool children (zero to five years of age) but the highest "at-risk" group comprised prepubescent boys. In 70% of cases, the bite was on a single lower limb. Of the 218 children who were admitted to hospital, 42% manifested local or systemic symptoms that were consistent with a confirmed snake-bite, irrespective of whether or not the species of snake was venomous. A positive identification of the genus of the offending snake was established in 18.8% of cases. In 35.8% of cases, the Commonwealth Serum Laboratories' Venom Detection Kit was used in an attempt to identify the involved snake, with 10 (4.6% of all cases) positive test-results. We have found that appropriate first aid was applied in the field in a maximum of 18% of cases. Antivenom was administered to 14 children, seven of whom received polyvalent antivenom; one child manifested a severe anaphylactic reaction. There were no fatalities in this series, and no permanent morbidity.

Snake venom hemorrhagins: neutralization by commercial antivenoms.

One monovalent (habu-antivenom) and five polyvalent antivenoms (Crotalidae; Orient, North, Central and South Africa) were tested for their ability to neutralize the hemorrhagic activity of 12 snake venoms (Agkistrodon, Bothrops, Crotalus, Sistrurus, Trimeresurus, Bitis, Echis spp.) when mixed prior to injection into the hind leg of mice. Considerable cross-neutralization was observed: antivenoms prepared against African snake venoms were equally or more potent in neutralizing the hemorrhagic activity of Crotalidae venoms. The same applies to Crotalidae antivenom which neutralized the activity of African snake venoms. Anti-hemorrhagic antibodies were isolated from a polyvalent antivenom by affinity chromatography using purified hemorrhagins from Bitis arietans and Crotalus adamanteus venom as ligands. These antibodies neutralized the activity of both hemorrhagins indicating common antigenic determinants in these molecules.

LD50 determination: objections to the method of Beccari as modified by Molinengo.

The efficiency of the method of Beccari as modified by Molinengo is compared with the sequential technique of Dixon and Mood. It is concluded that the sequential technique is less constrained, gives estimates that are less disperse and is simpler to analyze statistically than the regression of Beccari-Molinengo. Both techniques are comparable in the number of animals required, as well as in the time invested in each assay.

Funnel-web spider (Atrax robustus) antivenom. 1. Preparation and laboratory testing.

An antivenom to the Sydney Funnel-web Spider, Atrax robustus, developed in rabbits, passed exhaustive quality control studies and was subsequently tested in monkeys. It was shown to reverse the syndrome that follows envenomation in both a conscious unmonitored monkey and in two anaesthetised, monitored monkeys. This paper reports the results of these experiments. An autonomic crisis appears to be the major cause of mortality and morbidity in human victims and monkeys; this aspect of the syndrome is rapidly attenuated by the antivenom. We observed no ill-effects of antivenom.

Preparation of highly potent Naja naja atra (Formosan cobra) antivenin.

As the preparation of high titer antiserum against Naja naja atra venom is a time-consuming process, attempts were made to develop a immunization procedure for producing highly potent antiserums within a short period. Rabbits were immunized for 12 weeks with (1) whole venom as used routinely in our Institute, (II) whole venom adsorbed on carboxymethyl-cellulose (CMC) and mixed with Freund's complete adjuvant and (III) neurotoxin adsorbed on CMC and adjuvant mixture followed by CMC-whole venom-adjuvant mixture. The results showed that one ml of the antiserum prepared by method (III) could neutralize 445 LD50 of whole venom, in other words, its potency was 4 and 40 times higher than those prepared by methods (II) and (I), respectively.

Standardization of Vipera ammodytes antiserum.

The determination of the activity of viper antiserum in terms of the effective dose against 1 minimum lethal dose (MLD) of venom often leads to results which are not very reproducible. The present study concerns the preparation of a standard Vipera ammodytes antiserum and the choice of a suitable venom test dose. Portions of purified, concentrated antiserum were distributed into vacuum-sealed ampoules for use as a standard, and the amounts of this standard antiserum needed to neutralize various amounts of ammodytes venom were determined. The antivenin unit (AU) was fixed at 1.90 mg; 1 AU is the amount of standard serum required to protect 50% of white mice weighing 18 g against 0.05 mg (5 MLD) of venom. The use of the standard antiserum for titration of crude antisera in terms of this AU is described.